<?php

// +----------------------------------------------------------------------

// | OneThink [ WE CAN DO IT JUST THINK IT ]

// +----------------------------------------------------------------------

// | Copyright (c) 2013 http://www.onethink.cn All rights reserved.

// +----------------------------------------------------------------------

// | Author: 麦当苗儿 <zuojiazi@vip.qq.com> <http://www.zjzit.cn>

// +----------------------------------------------------------------------



/**

 * 系统非常规MD5加密方法

 * @param  string $str 要加密的字符串

 * @return string 

 */

function think_ucenter_md5($str, $key = 'ThinkUCenter'){

	return '' === $str ? '' : md5(sha1($str) . $key);

}



/**

 * 系统加密方法

 * @param string $data 要加密的字符串

 * @param string $key  加密密钥

 * @param int $expire  过期时间 (单位:秒)

 * @return string 

 */

function think_ucenter_encrypt($data, $key, $expire = 0) {

	$key  = md5($key);

	$data = base64_encode($data);

	$x    = 0;

	$len  = strlen($data);

	$l    = strlen($key);

	$char =  '';

	for ($i = 0; $i < $len; $i++) {

		if ($x == $l) $x=0;

		$char  .= substr($key, $x, 1);

		$x++;

	}

	$str = sprintf('%010d', $expire ? $expire + time() : 0);

	for ($i = 0; $i < $len; $i++) {

		$str .= chr(ord(substr($data,$i,1)) + (ord(substr($char,$i,1)))%256);

	}

	return str_replace('=', '', base64_encode($str));

}



/**

 * 系统解密方法

 * @param string $data 要解密的字符串 （必须是think_encrypt方法加密的字符串）

 * @param string $key  加密密钥

 * @return string 

 */

function think_ucenter_decrypt($data, $key){

	$key    = md5($key);

	$x      = 0;

	$data   = base64_decode($data);

	$expire = substr($data, 0, 10);

	$data   = substr($data, 10);

	if($expire > 0 && $expire < time()) {

		return '';

	}

	$len  = strlen($data);

	$l    = strlen($key);

	$char = $str = '';

	for ($i = 0; $i < $len; $i++) {

		if ($x == $l) $x = 0;

		$char  .= substr($key, $x, 1);

		$x++;

	}

	for ($i = 0; $i < $len; $i++) {

		if (ord(substr($data, $i, 1)) < ord(substr($char, $i, 1))) {

			$str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));

		}else{

			$str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));

		}

	}

	return base64_decode($str);

}

